Botryoidal agate is a fascinating and visually unique form of agate characterized by its bubbly, grape-like surface—making it a standout among more commonly banded agates. Botryoidal agate is a type of chalcedony, which is a microcrystalline variety of quartz. While typical agate forms in concentric bands, botryoidal agate is all about texture and shape. Its smooth, bubbly surface and subtle banding or color zoning make it highly sought after by collectors and lapidary artists.